Polyphasic Classification Of Novel Species Of Endophytic Actinomycetes From Medicinal Plants And Product Research

Objective:Four potential novel actinomycetes obtained from the internal tissues of medicinal plants in the early stage are taken as the research objects to study their polyphase classification and secondary metabolites,so as to fully exploit and utilize the rich resources of actinomycetes in China,efficiently discover novel antibiotics,accelerate the research and development of new microbial drugs in China,and provide a new research mode for solving the lag of research and development of new antibiotics.Methods:Firstly,the polyphasic approach,including cultural characteristics,physiological and biochemical characteristics,chemotaxonomic characteristics and phylogenetic analysis,was used to determine the taxonomic position of four potential novel actinomycetes.Secondly,strain M2CJ-2~T,a novel species of genus Streptomyces,was selected for genome sequencing and bioinformatics analysis.After fermentation,the fermentation broth was pretreated,and the secondary metabolites were separated by ODS column chromatography,gel column chromatography and high efficiency liquid separation.Results:The potential novel species of endophytic actinomycetes from medicinal plants,such as Nerium indicum Mill.(M8JJ-5~T),Scutellaria baicalensis Georgi(M1HQ-2~T),Mentha haplocalyx Briq.(N5BH11~T)and Cirsium japonicum Fisch.ex DC.(M2CJ-2~T)were identified.The complete genome sequencing and bioinformatics analysis of a novel actinomycete M2CJ-2~T were completed.There are 29 secondary metabolite synthesis gene clusters,which can encode and produce polyketones,non ribosomal peptides,terpenes,butyrolactones,bacteriocins,tetrahydropyrimidins,ferrocytes,?-inner esters,steranes and other compounds.The core structure of 10 out of 29 secondary metabolite synthetic gene clusters has been predicted,and 25synthetic gene clusters may encode curramycin,informatiptin,borelidin,landomycin,streptavericin,heronamide,feglycin,stenothericin,etc.Strain M2CJ-2~T also contains four new biosynthetic gene clusters,which may produce new compounds and the secondary metabolites of the strain M2CJ-2~T were studied.Currently,two compounds S5-2-1and S5-4-1 are obtained.Their structures remain to be resolved.Conclusion:Based on the analysis of phylogeny,phenotype and chemical composition,strain M8JJ-5~T represents a novel species of the genus Amnibacterium,named Amnibacterium flavum sp.nov.Strain M1HQ-2~T is a novel species of genus Brachybacterium,named Brachybacterium endophyticum sp.nov.Strain N5BH11~T represents a novel species of genus Nakamurella,named Nakamurella flava sp.nov.Strain M2CJ-2~T is a novel species of genus Streptomyces,named Streptomyces cirsii sp.nov.Strain M2CJ-2~T is rich in secondary metabolite synthesis gene cluster.It is an important resource for discovering new structural antibiotics from natural sources.